1. Field of the Invention
The present invention relates to the field of dielectric layer formation and more specifically to a method and apparatus for forming a titanium doped tantalum pentaoxide dielectric layer.
2. Discussion of Related Art
Integrated circuits are made up of literally millions of active and passive devices such as transistors, capacitors and resistors. In order to provide more computational power and/or more storage capability in an integrated circuit, device features are reduced or scaled down in order to provide higher packing density of devices. An important feature to enable scaling of devices is the ability to form high quality, high dielectric constant films for capacitor and gate dielectrics.
One high dielectric constant film that has been proposed is titanium doped tantalum pentaoxide. A conventional method of forming a titanium doped tantalum pentaoxide film is to first deposit a tantalum pentaoxide (Ta.sub.2 O.sub.5) film and then use ion implantation to dope the film with titanium atoms. A problem with doping the film with ion implantation is that the doping profile for flat surfaces (horizontal surfaces) will differ from that on side surfaces (vertical surfaces). Such differences in doping can cause the different areas to have different electrical properties which makes the process unacceptable in the manufacture of high density capacitors which utilize electrode designs with large aspect ratio openings (greater than 2:1). Additionally, ion implanting titanium atoms into a tantalum pentaoxide film can cause lattice destruction resulting in poor electrical performance such as high leakage currents.
Thus, what is desired is a method and apparatus for forming a titanium doped tantalum pentaoxide film.